Both myself and a local friend have done this on our own, as we hate the local Linn dealer. It's not too difficult. I did it with 5105's and 5140's, so I had to remove the crossovers too. I think the Ninka's have the newer crossovers that allow you to just change the wiring to go Activ. If so, lucky you!
The cards do come with instructions, but they weren't very helpful. In fact, had I followed the instructions and connected the crossovers to what the directions said, they wouldn't have worked at all. Seems the 5105's have two of the two pin connectors (this might be totally different for you, you'll have stereo cards for the LK85, I needed the mono cards for my 5105's), one is marked Activ, and isn't the one you use! Go figure!
I usually call Linn here in Florida for any questions, there's a guy in tech support named Willie who's always been a huge help with any questions I've had. He even sent me the cables and new software for my 5103, including the dealer instruction sheets!
Good luck and enjoy, Activ makes a huge difference in bass and punch!
BTW: DO make sure you mark the amps with the little stickers that come with the cards. It'll save you a lot of time when moving the system....which I just had the joy of doing! In other words...be sure to wire the speakers correctly!!!!
